1. Field of the Invention. This invention pertains to internal combustion engines, and more particularly to apparatus for controlling the proper operation of large diesel engines.
2. Description of the Prior Art. It is well known that internal combustion engines must be protected from operating under conditions that can damage to them. For example, lubrication oil pressure and cooling water temperature must fall within certain ranges if an engine is to perform satisfactorily over a long service life.
To protect internal combustion engines from the harmful effects of insufficient lubrication oil pressure, cooling water overtemperature, and other detrimental conditions, various protection devices have been developed. An example of prior protection devices includes that shown in U.S. Pat. No. 3,203,407, wherein a fuel shut-off is operated by compressed air. U.S. Pat. No. 4,178,901 shows a speed control that operates from a vehicle speedometer. The controls of both of the foregoing patents, as well as others, suffer the disadvantage of relying on secondary sensing and control systems that are interposed between the lubrication oil pressure and the engine fuel system, i.e., fuel flow is not controlled directly by the oil pressure itself. Further, electrical control systems such as that of the U.S. Pat. No. 4,178,901 are subject to tampering, such as by jumpering around various protection circuits.
U.S. Pat. No. 4,117,822 describes a protection device that is capable of being overridden by a person. The manual override limits and even defeats the usefulness of a protection system.
U.S. Pat. No. 4,120,275 discloses apparatus that operates in conjunction with an engine governor to increase fuel flow to the engine at engine startup when lubrication oil pressure is low. As the oil pressure increases, the fuel flow is decreased. The control of the U.S. Pat. No. 4,120,275 is not suitable for stopping an engine that loses lubrication oil pressure or that overheats.
In addition, none of the aforementioned devices is capable of protecting an engine from contaminated oil, which is a major cause of engine failure.
Thus, a need exists for a direct acting and tamper proof mechanism that protects an internal combustion engine against damage due to insufficient lubrication oil pressure.